docs: def _sigma_inel(self, Ep):
          """
          Inelastic cross-section for p-p interaction. KAB06 Eq. 73, 79
  
          Note: Quantities are not used in this function
  
          Parameters
          ----------
          Ep : float
              Eprot [TeV]
  
          Returns
          -------
          sigma_inel : float
              Inelastic cross-section for p-p interaction [1/cm2].
  
          """
          L = np.log(Ep)
          sigma = 34.3 + 1.88 * L + 0.25 * L ** 2
          if Ep <= 0.1:
              Eth = 1.22e-3
              sigma *= (1 - (Eth / Ep) ** 4) ** 2 * heaviside(Ep - Eth)
          return sigma * 1e-27